Inhibition of Steel Corrosion in Sulfuric Acid Solution by 1,10-Phenanthroline, para-Aminobenzoate and their Corresponding Manganese Complex

Abstract

Abstract The ligands 1,10-phenanthroline, (P) and para-aminobenzoate, (B); as well as their corresponding MnPB complex [bis-(dimanganese di-μ-paraaminobenzoate dichloro diphenanthroline)] have been investigated as inhibitors of mild steel corrosion in H2SO4 (0.5 M) solutions via potentiodynamic and electrochemical impedance spectroscopy techniques. Stability of the prepared complex was examined by UV-visible spectroscopy. The corrosion inhibition, thermodynamics, and adsorptive properties obtained have shown that MnPB complex has remarkable effects in the acidic solutions. Theoretical fitting of different adsorption isotherms such as Langmuir, Flory–Huggins, and the kinetic-thermodynamic models were tested and the thermodynamic activation parameters were calculated. The data revealed that the corrosion inhibition mechanism of mild steel in acidic solutions by the MnPB complex goes via physicochemical adsorption.